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Slit spacer - 6061 al - sub spindle / y axis lathe?

Rick_H

Plastic
Joined
Jan 26, 2013
Location
uk - midlands
Hoping to get some input on making this simple part - weighing up a dual spindle / y axis lathe at this point -

So we are getting more frequent and larger qty orders for a simple 6061 al cylindrical spacer approx 10mm tall (has some external features like a chamfer and OD groove) - The spacer is also slit 2mm (e.g spring washer)

So we use a 2 axis lathe, turn, part off, manually clean up back of spacer / part off burr and then slit them with a saw in a jig in one of the mills.

So my question - is it possible for one and done on a sub spindle lathe with y axis? Turn / slit, part off leaving some material on back, transfer to sub and then face back off / deburr?

My issue is how to transfer / hold the slit part without it compressing or expanding?

Any thoughts? Removing handling would save a huge amount of time here now.
 

ManualEd

Stainless
Joined
Oct 13, 2014
Location
Kelowna, Canada
Could make a custom collet/soft jaws that has a mandrel bolted to the collet chuck/3 jaw chuck.
Part slides over the mandrel then gets clamped. Probably not too difficult to do.

I think a sub spindle would be over kill for this. Any lathe with a Y would be good enough.
I'm a cheap-ass, so I'd use an ID tool to chamfer and part thru from the ID half way, chamfer and part off the rest of the OD should leave near-zero part off burr.
Probably throw the whole lot in a tumbler to see if it knocks off the rest of the burrs good enough.

Edit: Sub it to a swiss shop. Open a box every 10k parts to spot check, and never handle that stuff again.
 

Rick_H

Plastic
Joined
Jan 26, 2013
Location
uk - midlands
Could make a custom collet/soft jaws that has a mandrel bolted to the collet chuck/3 jaw chuck.
Part slides over the mandrel then gets clamped. Probably not too difficult to do.

I think a sub spindle would be over kill for this. Any lathe with a Y would be good enough.
I'm a cheap-ass, so I'd use an ID tool to chamfer and part thru from the ID half way, chamfer and part off the rest of the OD should leave near-zero part off burr.
Probably throw the whole lot in a tumbler to see if it knocks off the rest of the burrs good enough.

Edit: Sub it to a swiss shop. Open a box every 10k parts to spot check, and never handle that stuff again.

The mandrel inside of the chuck is something I have heard of - will look into that, I assume it’s not off the shelf solution, I’ll ask the apps guys at the machine dealer too.

De-burring is currently half the battle with these, we do chamfer from the back to reduce the size but it’s still there and cosmetics are important to this part - tumbling is a possibility but our in house setup hasn’t been massively successful there.

We are eyeing up a sub spindle lathe for other work anyway and parts are up to 2.5 inch in diameter so not very Swiss friendly.
 

Orange Vise

Stainless
Joined
Feb 10, 2012
Location
California
Yes, a sub with a quick-change collet system should work great on these.

For best efficiency, you'll want a subspindle lathe that is capable of doing a "push test", i.e. loads the subspindle servo during the transfer without actually crashing the two chucks together. It ensures that the part is fully seated in the Z-axis of the subspindle chuck. If the machine doesn't have that feature, you can still accomplish something similar by having some sort of spring loaded device on any free station on the backside of the turret to push the part with an open/close cycle of the sub.

Use that in conjunction with custom stepped collets that have an ID larger than the washer ID so that a parts ejector can knock out the parts. The collet should also have a shallow counterbore sized nominally to the washer OD. You'll need a different collet for every sized washer and the cost adds up, but it's worth it if these parts pay well and are ordered in high enough quantities. This setup ensures reliable handoffs and consistent length control. The bars should come out burr-free with nice looking chamfers on both sides and excellent facing finishes on both sides as well.

I wouldn't use a 3-jaw chuck on the sub in this application. Time consuming and less reliable in setups. 3-jaw on the main is fine, although a collet is still preferable.

Cost justification of an automated machine should always be evaluated with labor in mind. IME brute force labor only beats automation in small quantities.
 
Last edited:

Rick_H

Plastic
Joined
Jan 26, 2013
Location
uk - midlands
Yes, a sub with a quick-change collet system should work great on these.

For best efficiency, you'll want a subspindle lathe that is capable of doing a "push test", i.e. loads the subspindle servo during the transfer without actually crashing the two chucks together. It ensures that the part is fully seated in the Z-axis of the subspindle chuck. If the machine doesn't have that feature, you can still accomplish something similar by having some sort of spring loaded device on any free station on the backside of the turret to push the part with an open/close cycle of the sub.

Use that in conjunction with custom stepped collets that have an ID larger than the washer ID so that a parts ejector can knock out the parts. The collet should also have a shallow counterbore sized nominally to the washer OD. You'll need a different collet for every sized washer and the cost adds up, but it's worth it if these parts pay well and are ordered in high enough quantities. This setup ensures reliable handoffs and consistent length control. The bars should come out burr-free with nice looking chamfers on both sides and excellent facing finishes on both sides as well.

I wouldn't use a 3-jaw chuck on the sub in this application. Time consuming and less reliable in setups. 3-jaw on the main is fine, although a collet is still preferable.

Cost justification of an automated machine should always be evaluated with labor in mind. IME brute force labor only beats automation in small quantities.

Thanks for the info - really helpful, will get onto the machine supplier about part transfer loading as that’s not something that had crossed my mind.

The parts are a real pain in terms of mill second operating for slitting and manual finishing - labour isn’t cheap and it’s tedious work but a good repeat customer we want to keep happy and probably about time we added some turning capacity outside of basic 2 axis.
 

Orange Vise

Stainless
Joined
Feb 10, 2012
Location
California
Thanks for the info - really helpful, will get onto the machine supplier about part transfer loading as that’s not something that had crossed my mind.
One other trick if the machine can't preload the sub is to have your turret grab the bar with a barpuller, unclamp the main and have the sub push against the bar. The bar will drag against the barpuller, providing some preload against the sub collet. That can ensure reasonably good length control.

The bar will move backwards slightly in the main, so your sub will pull it back out after clamping to perform the part-off.
 
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Eric U

Hot Rolled
Joined
Feb 26, 2003
Location
Eastern AL
No need for subspindle...as I have none. The pictured part was turned/milled complete before parting off from the bar. I used a back chamfer milling tool to do the back ID chamfer, then I added the OD back side chamfer with a regular chamfer mill, then parted off to length. The parts are aluminum so it was a simple thing to run the back side across some fine sandpaper to remove the very slight burr. Even if I had a subspindle, the idea of trying to get that slit on some kind of spacer to keep the part from collapsing seems pretty daunting.

Simple split spacers should be a much simpler job.

SCATT Mount Back.jpg
SCATT Mount Front.jpg
 

Rick_H

Plastic
Joined
Jan 26, 2013
Location
uk - midlands
No need for subspindle...as I have none. The pictured part was turned/milled complete before parting off from the bar. I used a back chamfer milling tool to do the back ID chamfer, then I added the OD back side chamfer with a regular chamfer mill, then parted off to length. The parts are aluminum so it was a simple thing to run the back side across some fine sandpaper to remove the very slight burr. Even if I had a subspindle, the idea of trying to get that slit on some kind of spacer to keep the part from collapsing seems pretty daunting.

Simple split spacers should be a much simpler job.

View attachment 369796
View attachment 369797
Thanks for the reply - our parts are much more simple and round so no need to align the slot.

Nice work and example - I wish we had live tooling on our lathe, we are more of a mill shop so only got one 2 axis….
 








 
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